It *could* be the release bearing or a problem with the clutch pressure plate.. but that's a gearbox-off job to investigate, which is not going to be cheap.
If you have to take it apart, fit a new clutch and bearing regardless of what yours look like, since it'll mean you won't have to do it again for a very long time. Labour is most of the bill. The clutch kit itself won't be a lot more, if you buy a decent aftermarket one (Valeo, Luk etc.).
If your clutch feels okay then assume it is okay... so before dismantling everything first check the other likely causes.
I dunno if this noise is the same whining noise you described in your other post.. If this is a new/different noise, try bleeding the clutch and have a look at the slave cylinder, if it's an external one on top of the gearbox. The pushrod gets covered in road grime so the slave can become lumpy (vague pedal) and then eventually fail (leaking fluid on top of the gearbox is a sign). They're actually cheap and relatively easy to replace when they're external.
If your slave cylinder is a Concentric type (inside the gearbox) then you can bleed it.. but you're back at "gearbox off" to inspect it.
Ralf S.